Prevention Of Venous Thromboembolism In Orthopedic Surgery Research Articles

Efficacy and Toxicity of Factor Xa Inhibitors

Venous thromboembolism (VTE) is a serious disease that is often neglected, and effective and safe antithrombotic treatments are a public health priority. New antithrombotics such as rivaroxaban, apixaban, betrixaban, edoxaban, darexaban, TAK-442, LY517717, eribaxaban, otamixaban are being developed to overcome current therapeutic limitations. The new oral anticoagulants and parenteral otamixaban are under evaluation in clinical trials for VTE treatment, for VTE prevention in orthopedic surgery, for stroke prevention in patients with atrial fibrillation and for cardiovascular event prevention in patients with acute coronary syndrome. These antithrombotic agents directly and selectively inhibit factor Xa, and do not require coagulation monitoring and dose adjustment. Several of these drugs have shown promising results and have the potential to either replace or act as alternatives to traditional anticoagulants (heparins, vitamin K antagonists).

Dabigatran in the prevention of venous thromboembolism after major orthopedic surgery

Venous thromboembolism (VTE) is a very frequent surgical complication, especially in major orthopedic procedures. Prophylaxis with pharmacological agents, including warfarin and subcutaneous injection of either low-molecular weight heparin (LMWH) or low-dose unfractionated heparin, and/or with mechanical methods has been shown to be effective and safe. Despite recommendations on the routine implementation of these prophylaxis methods, some surveys demonstrate that many patients currently don’t receive any prophylaxis. The recent introduction of dabigatran etexilate, a novel oral direct thrombin inhibitor approved for VTE prophylaxis in total knee and hip substitution, represents a major advance in the provision of efficient anticoagulation therapy. Two pivotal randomized controlled multicenter trials assessed non-inferiority of dabigatran 150/220 mg/day versus enoxaparin 40 mg/day in the prevention of VTE after hip and knee replacement. From an economical point of view, an English modeling study on dabigatran cost/effectiveness showed it to be associated with lower cost and slightly higher gain in Quality Adjusted Life Years, thus dominating enoxaparin. Other analyses obtained results consistent with these, estimating inferior costs related to the use of dabigatran with respect to low weight heparin; this difference was mainly due to health personnel work for heparins subcutaneous administration. In Italy, acquisition costs for a 28-35 days therapeutic cycle of main antithrombotic drugs vary between 70 and 170 €, according to different distribution policy. Dabigatran, with a cost of 117 €, holds a medial position. Cost savings related to oral administration may partially offset the price difference between dabigatran and the less expensive options among LMWHs or, compared with the more expensive ones, add to pharmaceutical cost savings. In order to increase the effectiveness of VTE prophylaxis, the improvement of patient adherence to the prescribed strategy is needed. On this plane, dabigatran may be associated to some advantages, like the lack of drug and food interactions, the need for less frequent coagulation monitoring compared to vitamin K antagonists, and obviation of daily injections of parenteral agents. In conclusion, these considerations suggest that dabigatran may prove an interesting alternative in VTE prevention in orthopedic surgery.

Use of Emerging Oral Anticoagulants in Clinical Practice

A review of clinical data from oral anticoagulant studies in orthopedic/general surgery and extrapolation to actual clinical practice. In all surgical patients, there is a risk of postoperative venous thromboembolism (VTE). Parenteral unfractionated heparin, low-molecular-weight heparin, and fondaparinux are available for VTE prophylaxis. Vitamin K antagonists, the only available oral anticoagulants, are widely used in the United States for thromboprophylaxis in joint replacement surgery in spite of being associated with several disadvantages, limiting their effectiveness in the postoperative setting. The oral direct thrombin inhibitor ximelagatran, briefly approved outside the United States for thromboprophylaxis in orthopedic patients, was discontinued due to severe hepatotoxicity concerns. Recently, the oral factor Xa inhibitors rivaroxaban and apixaban have entered late phase development for VTE thromboprophylaxis and treatment and the oral direct thrombin inhibitor dabigatran has received marketing approval from the European Medicines Agency. Review of clinical studies of the oral anticoagulants in VTE prevention in orthopedic surgery and comparison with large observational registries. : Results from Phase II/III studies suggest that new oral anticoagulants may provide an efficacious alternative in VTE prevention in orthopedic surgery. Furthermore, these new oral agents have, so far, shown a good overall safety profile, with no evidence of increased hepatotoxicity. However, comparison with large observational registries reveals differences between real-life patient populations, which make extrapolation of clinical trial data to actual clinical practice difficult. Differences in endpoint definitions also prevent indirect comparison of agents. Specific compliance and postmarketing safety issues (especially liver enzyme monitoring requirements) need to be clarified before these agents are widely accepted into routine clinical practice. Although new oral anticoagulants appear promising, clinical trial results should be viewed with caution until they can be replicated in routine care settings across a broad spectrum of surgical patients.